Refrigerator and method of controlling the same

ABSTRACT

A method of controlling a refrigerator is disclosed. The method includes: operating a cool air supply means with a predetermined output; a controller determining the output of the cool air supply means based on a current temperature of a storage compartment sensed by a temperature sensor while the cool air supply means operates with the predetermined output; and the controller operating the cool air supply means with the determined output. The controller determines that the output of the cool air supply means is decreased or increased when an absolute value of a difference between a previous temperature and a current temperature of the storage compartment is equal to or greater than a first reference value, and wherein the output of the cool air supply means is decreased or increased again when the absolute value of the difference between a current temperature of the storage compartment sensed again after a predetermined time has elapses and the previous temperature of the storage compartment is equal to or greater than the first reference value.

TECHNICAL FIELD

The present invention relates to a refrigerator and a method ofcontrolling the same.

BACKGROUND ART

Refrigerators are home appliance for storing food at low temperature. Astorage compartment needs to be kept at a constant low temperature. Inthe case of current household refrigerators, a storage compartment ismaintained within a range between an upper limit temperature and a lowerlimit temperature based on a set temperature. That is, the refrigeratoris controlled using a method of performing a refrigerating cycle to coolthe storage compartment when the temperature of the storage compartmentincreases to the upper limit temperature and stopping the refrigeratingcycle when the temperature of the storage compartment decreases to thelower limit temperature.

Korean Patent Laid-Open Publication No. 1997-0022182 (Publication Date:May 28, 1997) discloses a constant temperature control method formaintaining a storage compartment of a refrigerator at a constanttemperature.

According to the related art, a compressor and a fan are driven and, atthe same time, a storage compartment damper is fully opened when thetemperature of the storage compartment is higher than a set temperature,and the compressor and the fan are stopped and, at the same time, thestorage compartment is closed when the temperature of the storagecompartment is cooled to the set temperature.

The method of controlling the refrigerator according to the related arthas the following problems.

First, since a process of driving the compressor when the temperature ofthe storage compartment of the refrigerator is increased to the settemperature or higher and stopping the compressor when the temperatureof the storage compartment is decreased to the set temperature or loweris repeated, change in temperature of the storage compartment is largeand thus freshness of food stored in the storage compartment may belowered.

In addition, since the compressor is repeatedly driven and stopped,power consumption is increased when the compressor is driven again.

In addition, when the storage compartment damper is fully opened, thereis a high possibility that cool air is excessively supplied to thestorage chamber in a state in which the damper is fully opened, therebyovercooling the storage compartment.

DISCLOSURE OF INVENTION Technical Problem

An object of the present invention devised to solve the problem lies ina refrigerator for maintaining a storage compartment at a constanttemperature in order to improve freshness of objects, and a method ofcontrolling the same.

Another object of the present invention devised to solve the problemlies in a refrigerator capable of reducing power consumption of a coolair supply means while maintaining a storage compartment at a constanttemperature, and a method of controlling the same.

Another object of the present invention devised to solve the problemlies in a refrigerator capable of rapidly returning to a constanttemperature when the temperature of a storage compartment deviates fromthe constant temperature, and a method of controlling the same.

Solution to Problem

The object of the present invention can be achieved by providing amethod of controlling a refrigerator including operating a cool airsupply means with a predetermined output, a controller determining theoutput of the cool air supply means based on a current temperature of astorage compartment sensed by a temperature sensor while the cool airsupply means operates with the predetermined output, and the controlleroperating the cool air supply means with the determined output.

For example, the controller may determine that the output of the coolair supply means is decreased or increased when an absolute value of adifference between a previous temperature and a current temperature ofthe storage compartment is equal to or greater than a first referencevalue, and the output of the cool air supply means may be decreased orincreased again when the absolute value of the difference between acurrent temperature of the storage compartment sensed again after apredetermined time has elapses and the previous temperature of thestorage compartment is equal to or greater than the first referencevalue.

For example, the controller may determine that the output of the coolair supply means is decreased when the difference between the previoustemperature and the current temperature of the storage compartment isgreater than 0 and the absolute value of the difference between theprevious temperature and the current temperature of the storagecompartment is equal to or greater than the first reference value.

The controller may determine that the output of the cool air supplymeans is increased when the difference between the previous temperatureand the current temperature of the storage compartment is less than 0and the absolute value of the difference between the previoustemperature and the current temperature of the storage compartment isequal to or greater than the first reference value.

The controller may determine that the output of the cool air supplymeans is decreased or increased by a first level when the absolute valueof the difference between the previous temperature and the currenttemperature of the storage compartment is equal to or greater than thefirst reference value and is less than a second reference value greaterthan the first reference value, and determine that the output of thecool air supply means is decreased or increased by a second levelgreater than the first level when the absolute value of the differencebetween the previous temperature and the current temperature of thestorage compartment is equal to or greater than the second referencevalue.

A difference between the second reference value and the first referencevalue, and the first reference value may be equal or different.

When change in the output of the cool air supply means corresponding tothe first level is referred to as a first output change value and changein the output of the cool air supply means corresponding to the secondlevel is referred to as a second output change value, a differencebetween the second output change value and the first output change valuemay be equal to or different from the first output change value.

For example, the controller may determine that the output of the coolair supply means is maintained when the absolute value of the differencebetween the previous temperature and the current temperature of thestorage compartment is less than the first reference value.

The cool air supply means may include one or more of a compressorconfigured to compress refrigerant and a fan driver configured to drivea fan for blowing air heat-exchanged with an evaporator to the storagecompartment.

The storage compartment may be a refrigerating compartment, and the coolair supply means may include a damper driver configured to drive adamper provided in a duct for guiding cool air of a freezing compartmentto the refrigerating compartment.

In another aspect of the present invention, provided herein is a methodof controlling a refrigerator including operating a cool air supplymeans with a predetermined output, a controller determining the outputof the cool air supply means based on a current temperature of a storagecompartment sensed by a temperature sensor while the cool air supplymeans operates with the predetermined output, and the controlleroperating the cool air supply means with the determined output, whereinthe controller determines that the output of the cool air supply meansis decreased or increased when an absolute value of a difference betweena set temperature and a current temperature of the storage compartmentis equal to or greater than a first reference value, and wherein theoutput of the cool air supply means is decreased or increased again whenthe absolute value of the difference between the set temperature and acurrent temperature of the storage compartment sensed again after apredetermined time has elapses is equal to or greater than the firstreference value.

The first reference value may include a first upper limit referencevalue higher than the set temperature, and, when the current temperatureis higher than the set temperature and the absolute value of thedifference between the set temperature and the current temperatureexceeds the first upper limit reference value, the controller maydetermine that the output of the cool air supply means is increased.

The first reference value may include a first lower limit referencevalue higher than the set temperature, and, when the current temperatureis lower than the set temperature and the absolute value of thedifference between the set temperature and the current temperatureexceeds the first lower limit reference value, the controller maydetermine that the output of the cool air supply means is decreased.

The controller may determine that the output of the cool air supplymeans is decreased or increased by a first level when the absolute valueof the difference between the set temperature and the currenttemperature of the storage compartment is equal to or greater than thefirst reference value and is less than a second reference value greaterthan the first reference value, and determine that the output of thecool air supply means is decreased or increased by a second levelgreater than the first level when the absolute value of the differencebetween the set temperature and the current temperature of the storagecompartment is equal to or greater than the second reference value.

The controller may determine that the output of the cool air supplymeans is maintained when the absolute value of the difference betweenthe set temperature and the current temperature of the storagecompartment is less than the first reference value.

The cool air supply means may include one or more of a compressorconfigured to compress refrigerant and a fan driver configured to drivea fan for blowing air heat-exchanged with an evaporator to the storagecompartment.

The storage compartment may be a refrigerating compartment, and the coolair supply means may include a damper driver configured to drive adamper provided in a duct for guiding cool air of a freezing compartmentto the refrigerating compartment.

In another aspect of the present invention, provided herein is a methodof controlling a refrigerator including sensing whether the refrigeratoris turned on; changing an output of a cool air supply means to apredetermined first output value after the refrigerator is turned on;stopping the cool air supply means when a temperature of a storagecompartment reaches an OFF reference temperature A2 lower than a settemperature of the storage compartment; a controller determining theoutput of the cool air supply means to a second output value lower thanthe predetermined first output value based on a current temperature of astorage compartment sensed by a temperature sensor when the temperatureof the storage compartment reaches a predetermined temperature; and thecontroller operating the cool air supply means with the determinedoutput.

The operating the cool air supply means with determined second outputmay include: when a range between a temperature upper limit greater thana set temperature of the storage compartment and a temperature lowerlimit less than the set temperature of the storage compartment is atemperature satisfaction range, the controller determining that theoutput of the cool air supply means is maintained when the sensedcurrent temperature is in the temperature satisfaction range and anabsolute value of a difference between a previous temperature and thecurrent temperature of the storage compartment is less than a firstreference value, and the controller changing the output of the cool airsupply means when the sensed current temperature is out of thetemperature satisfaction range or the absolute value of the differencebetween the previous temperature and the current temperature of thestorage compartment is equal to or more than the first reference value.

When it is determined that a refrigerator door is opened or the cool airsupply means is stopped for defrosting, the controller determines theoutput of the cool air supply means to a third output value differentfrom the second output value.

The third output value may be equal to the first output value or may beless than the second output value.

Advantageous Effects of Invention

According to embodiments, since the temperature of the storagecompartment can be constantly maintained, the storage period of food canbe increased. That is, food stored in the storage compartment isprevented from being overcooled or wilted.

In addition, in order to constantly maintain the temperature of thestorage compartment, since a cool air supply means is not stopped and ismaintained in a driving state, power consumed for initial startup of thecool air supply means can be reduced.

In addition, since the output of the cool air supply means is controlledbased on a difference between a previous temperature and a currenttemperature and/or a difference between a set temperature and a currenttemperature, it is possible to rapidly return to a constant temperaturewhen the temperature of the storage compartment deviates from theconstant temperature.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a refrigerator according to anembodiment of the present invention.

FIG. 2 is a schematic view showing the configuration of a refrigeratoraccording to an embodiment of the present invention.

FIG. 3 is a block diagram of a refrigerator of the present invention.

FIG. 4 is a flowchart illustrating a method of controlling arefrigerator according to a first embodiment of the present invention.

FIG. 5 is a graph illustrating change in temperature of a storagecompartment and output control of a cool air supply means according tothe first embodiment.

FIG. 6 is a flowchart illustrating a method of controlling arefrigerator according to a second embodiment of the present invention.

FIG. 7 is a graph illustrating change in temperature of a storagecompartment and output control of a cool air supply means according tothe second embodiment.

FIG. 8 is a flowchart illustrating a method of controlling arefrigerator according to a third embodiment of the present invention.

FIGS. 9 to 12 are flowcharts illustrating a method of controlling theoutput of a cool air supply means according to the third embodiment.

FIG. 13 is a graph illustrating change in temperature of a storagecompartment and output control of a cool air supply means according tothe third embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, exemplary embodiments of the present invention will bedescribed below in detail with reference to the accompanying drawings inwhich the same reference numbers are used throughout this specificationto refer to the same or like parts. In describing the present invention,a detailed description of known functions and configurations will beomitted when it may obscure the subject matter of the present invention.

It will be understood that, although the terms first, second, A, B, (a),(b), etc. may be used herein to describe various elements of the presentinvention, these terms are only used to distinguish one element fromanother element and essential, order, or sequence of correspondingelements are not limited by these terms. It will be understood that whenone element is referred to as “being connected to”, “being coupled to”,or “accessing” another element, one element may “be connected to”, “becoupled to”, or “access” another element via a further element althoughone element may be directly connected to or may directly access anotherelement.

FIG. 1 is a perspective view of a refrigerator according to anembodiment of the present invention, FIG. 2 is a schematic view showingthe configuration of a refrigerator according to an embodiment of thepresent invention, and FIG. 3 is a block diagram of a refrigerator ofthe present invention.

Referring to FIGS. 1 to 3, the refrigerator 1 according to oneembodiment of the present invention may include a cabinet 11 having astorage compartment formed therein and a storage compartment doorcoupled to the cabinet 11 to open and close the storage compartment.

The storage compartment includes a freezing compartment 111 and arefrigerating compartment 112. The freezing compartment 111 and therefrigerating compartment 112 may store an object such as food.

The freezing compartment 111 and the refrigerating compartment 112 maybe partitioned by a partitioning wall 113 inside the cabinet 11 in ahorizontal or vertical direction.

The storage compartment door may include a freezing compartment door 15for opening and closing the freezing compartment 111 and a refrigeratingcompartment door 16 for opening and closing the refrigeratingcompartment 112. The refrigerating compartment door 16 may furtherinclude a sub door 17 for withdrawing an object stored in therefrigerating compartment door without opening the refrigeratingcompartment door 16, without being not limited thereto.

The partitioning wall 113 includes a connection duct (not shown) forproviding a cool air passage for supplying cool air to the refrigeratingcompartment 112. A damper 12 may be installed in the connection duct(not shown) to open or close the connection duct.

In addition, the refrigerator 1 may further include a refrigeratingcycle 20 for cooling the freezing compartment 111 and/or therefrigerating compartment 112.

Specifically, the refrigerating cycle 20 includes a compressor 21 forcompressing refrigerant, a condenser 22 for condensing refrigerantpassing through the compressor 21, an expansion member 23 for expandingrefrigerant passing through the condenser 22, and an evaporator 24 forevaporating refrigerant passing through the expansion member 23. Theevaporator 24 may include a freezing compartment evaporator, forexample.

In addition, the refrigerator 1 may include a fan 26 for enabling air toflow toward the evaporator 24 for circulation of cool air in thefreezing compartment 111 and a fan driver 25 for driving the fan 26.

In the present embodiment, the compressor 21 and the fan driver 25 areoperated in order to supply cool air to the freezing compartment 111,and not only the compressor 21 and the fan driver 25 are operated butalso the damper 12 is opened in order to supply cool air to therefrigerating compartment 112. At this time, the damper 12 may beoperated by the damper driver 13.

In this specification, the compressor 21, the fan driver 25 and thedamper 12 (or the damper driver) may be referred to as a “cool airsupply means” which operate to supply to cool air to the storagecompartment.

In this specification, when the cool air supply means includes thecompressor 21 and the fan driver 25, “operating or turning on the coolair supply means” means that the compressor 21 and the fan driver 25 areturned on and “stopping or turning off the cool air supply means” meansthat the compressor 21 and the fan driver 25 are turned off.

In this specification, when the cool air supply means includes thecompressor 21 and the fan driver 25, the output of the cool air supplymeans the cooling power of the compressor 21 and the rotational speed ofthe fan driver 25.

In addition, when the cool air supply means is the damper 12, “operatingor turning on the cool air supply means” means that the damper 12 opensa flow passage such that cool air of the freezing compartment 111 flowsto the refrigerating compartment 112, and “stopping or turning off thecool air supply means” means that the damper 12 closes the flow passagesuch that cool air of the freezing compartment 111 does not flow to therefrigerating compartment 112.

When the cool air supply means is the damper 12 (or the damper driver),increasing the output of the cool air supply means that the openingangle of the damper 12 is increased and decreasing the output of thecool air supply means that the opening angle of the damper 12 isdecreased.

The refrigerator 1 may include a freezing compartment temperature sensor41 for sensing the temperature of the freezing compartment 111, arefrigerating compartment temperature sensor 42 for sensing thetemperature of the refrigerating compartment 112, and a controller 50for controlling the cool air supply means based on the temperaturessensed by the temperature sensors 41 and 42.

The controller 50 may control one or more of the compressor 21 and thefan driver 25 in order to maintain the temperature of the freezingcompartment 111 at a target temperature.

For example, the controller 50 may increase, maintain or decrease theoutput of the fan driver 25 and the compressor 21.

In addition, the controller 50 may increase, maintain or decrease theoutput of one or more of the compressor 21, the fan driver 25 and thedamper 12 (or the damper driver 13) in order to maintain the temperatureof the refrigerating compartment 112 at the target temperature.

For example, the controller 50 may change the opening angle of thedamper 12 while the compressor 21 and the fan driver 25 are operatingwith constant output.

A set temperature (or a target temperature) may be stored in a memory52. In addition, change in unit cooling power according to unittemperature may be stored.

In this specification, a temperature higher than the target temperatureof the refrigerating compartment 112 may be referred to as a firstrefrigerating compartment reference temperature and a temperature lowerthan the target temperature of the refrigerating compartment 112 may bereferred to as a second refrigerating compartment reference temperature.

In addition, a temperature higher than the target temperature of thefreezing compartment 111 may be referred to as a first freezingcompartment reference temperature and a temperature lower than thetarget temperature of the freezing compartment 111 may be referred to asa second freezing compartment reference temperature.

In addition, a range between the first refrigerating compartmentreference temperature and the second refrigerating compartment referencetemperature may be referred to as a refrigerating compartmenttemperature satisfaction range. A predetermined temperature between thefirst refrigerating compartment reference temperature and the secondrefrigerating compartment reference temperature may be referred to as afirst set temperature. The first set temperature may be a targettemperature or an average temperature of the first refrigeratingcompartment reference temperature and the second refrigeratingcompartment reference temperature.

In addition, a range between the first freezing compartment referencetemperature and the second freezing compartment reference temperaturemay be referred to as a freezing compartment temperature satisfactionrange. A predetermined temperature between the first freezingcompartment reference temperature and the second freezing compartmentreference temperature may be referred to as a second set temperature.The second set temperature may be a target temperature or an averagetemperature of the first freezing compartment reference temperature andthe second freezing compartment reference temperature.

The controller 50 may control the cool air supply means such that thetarget temperatures of the freezing compartment 111 and/or therefrigerating compartment 112 are maintained within the temperaturesatisfaction ranges.

Hereinafter, a constant temperature control method of a storagecompartment will be described.

FIG. 4 is a flowchart illustrating a method of controlling arefrigerator according to a first embodiment of the present invention.

Referring to FIG. 4, the controller 50 performs preliminary operationfor constant temperature control (S2), when the refrigerator 1 is turnedon (S1).

In this specification, the cool air supply means may be turned on whenthe temperature of the storage compartment is greater than an ONreference temperature A1 and may be turned off when the temperature ofthe storage compartment is less than an OFF reference temperature A2.

In general, when the refrigerator 1 is turned on or the cool air supplymeans is turned on in a state in which the refrigerator 1 is turned offor the cool air supply means is turned off for defrosting, since thetemperature of the storage compartment is higher than the ON referencetemperature A1, the controller 50 may perform control such that thetemperature of the storage compartment is rapidly decreased, that is,the cool air supply means operates with a predetermined first outputvalue, for example, a maximum output value.

For example, the controller 50 may perform control such that thecompressor 21 operates with maximum cooling power, and the opening angleof the damper 12 may be maximized.

When the compressor 21 operates with maximum cooling power, thetemperature of the storage compartment is decreased and, when thetemperature of the storage compartment becomes less than the OFFreference temperature A2, the controller 50 may stop the compressor 21.Alternatively, the controller 50 may close the damper 12.

That is, the preliminary operation step may include step of operatingthe cool air supply means with the maximum output and step of stoppingthe cool air supply means.

During the preliminary operation of the refrigerator, the controller 50determines whether a constant temperature control start condition issatisfied (S3).

For example, the controller 50 may determine whether the temperature ofthe storage compartment reaches the set temperature in a state in whichthe cool air supply means is stopped.

In a state in which the cool air supply means is stopped, thetemperature of the storage compartment is increased, and, when thetemperature of the storage compartment reaches the set temperature, thecontroller 50 determines that the constant temperature control startcondition is satisfied and performs constant temperature control of thestorage compartment.

When the constant temperature control start condition is satisfied, thecool air supply means operates with predetermined output (a secondoutput value less than the first output value) (S4). The predeterminedoutput is between minimum output and maximum output.

In the constant temperature control step, the cool air supply means maycontinuously operate.

The constant temperature control step may include step S5 of sensing thetemperature of the storage compartment at a predetermined time intervaland step S6 of controlling the output of the cool air supply means.

In the present embodiment, the controller 50 may control the output ofthe cool air supply means in order to perform constant temperaturecontrol of the storage compartment and may control the output of thecool air supply means based on the temperature of the storagecompartment.

Specifically, the controller 50 determines change in temperature of thestorage compartment and controls the output of the cool air supply means(S6).

In the present embodiment, a difference between a previous temperatureof the storage compartment (hereinafter, referred to as a “previoustemperature”) and a current temperature of the storage compartment(hereinafter, referred to as a current temperature) is used as change intemperature of the storage compartment.

Change in temperature of storage compartment is based on the temperaturevalue of the storage compartment sensed at the predetermined timeinterval. Accordingly, the predetermined time is a sampling time fordetermining change in temperature.

At this time, the sampling time may be constant or changed according toa current temperature. For example, if the current temperature islocated in the first temperature range, a first sampling time isapplicable as a sampling time for sensing a current temperature of anext time.

In contrast, if the current temperature is located in a secondtemperature range, a second sampling time greater or less than the firstsampling time is applicable as a sampling time for sensing a currenttemperature of a next time.

The controller 50 continuously perform constant temperature controlunless the refrigerator 1 is turned off (S7).

FIG. 5 is a graph illustrating change in temperature of a storagecompartment and output control of a cool air supply means according tothe first embodiment.

FIG. 5 shows change in cooling power of the compressor for maintainingthe freezing compartment at a constant temperature and change intemperature of the freezing compartment. Numbers on the graph areexamples of the cooling power of the compressor.

Hereinafter, control of the cooling power of the compressor as anexample of the cool air supply means will be described.

Referring to FIG. 5, after the refrigerator is turned on or defrostingoperation is finished, the compressor 21 may operate with the maximumcooling power in order to rapidly decrease the temperature of thefreezing compartment. When the temperature of the freezing compartmentreaches the OFF reference temperature A2, the compressor 21 is stopped.

When the compressor 21 is stopped, the temperature of the freezingcompartment is increased and, when the temperature of the freezingcompartment reaches the set temperature Notch, constant temperaturecontrol of the freezing compartment may start.

When constant temperature control of the freezing compartment starts,the compressor 21 operates with predetermined cooling power betweenminimum cooling power and maximum cooling power.

As described above, the temperature of the freezing compartment issensed at a sampling time interval, and the controller 50 controls thecooling power of the compressor 21 based on a difference between aprevious temperature and a current temperature.

For example, while the compressor 21 operates with cooling power of 60,the cooling power may be maintained (cooling power: 60), decreased(cooling power: 55 or 50) or increased (cooling power: 65 or 70),according to the temperature of the freezing compartment.

For example, when an absolute value of the difference between theprevious temperature and the current temperature is less than a firstreference value, the controller 50 may maintain the cooling power of thecompressor 21.

Alternatively, when an absolute value of the difference between theprevious temperature and the current temperature is equal to or greaterthan the first reference value, the controller 50 may increase ordecrease the cooling power of the compressor 21.

For example, when the difference between the previous temperature andthe current temperature is greater than 0 and the absolute value of thedifference between the previous temperature and the current temperatureis equal to or greater than the first reference value, the cooling powerof the compressor 21 may be decreased by a first level.

Alternatively, when the difference between the previous temperature andthe current temperature is less than 0 and the absolute value of thedifference between the previous temperature and the current temperatureis equal to or greater than the first reference value, the cooling powerof the compressor 21 may be increased by the first level.

In the present embodiment, a plurality of reference values forcomparison with the absolute value of the difference between theprevious temperature and the current temperature may be set.

For example, when the difference between the previous temperature andthe current temperature is greater than 0 and the absolute value of thedifference between the previous temperature and the current temperatureis equal to or greater than a second reference value greater than thefirst reference value, the cooling power of the compressor 21 may bedecreased by a second level. In addition, when the absolute value of thedifference between the previous temperature and the current temperatureis equal to or greater than a third reference value greater than thesecond reference value, the cooling power of the compressor 21 may bedecreased by a third level.

Alternatively, when the difference between the previous temperature andthe current temperature is less than 0 and the absolute value of thedifference between the previous temperature and the current temperatureis equal to or greater than the second reference value greater than thefirst reference value, the cooling power of the compressor 21 may beincreased by the second level. In addition, when the absolute value ofthe difference between the previous temperature and the currenttemperature is equal to or greater than the third reference valuegreater than the second reference value, the cooling power of thecompressor 21 may be increased by the third level.

At this time, the differences between the reference values may be equalor different.

For example, the first reference value may be set to 0.5, the secondreference value may be set to 1, and the third reference value may beset to 1.5. Alternatively, the first reference value may be set to 0.5,the second reference value may be set to 0.9, and the third referencevalue may be set to 1.3.

In addition, the differences between the plurality of levels may beequal or different.

For example, the first level may be set to A as a cooling power changevalue, the second level may be set to 2*A as a cooling power changevalue, and the third level may be set to 3*A as a cooling power changevalue. Alternatively, the first level may be set to A as a cooling powerchange value, the second level may be set to B (greater than A) which isnot 2*A as a cooling power change value, and the third level may be setto C (greater than B) which is not 3*A as a cooling power change value.

Meanwhile, in a state in which the cooling power of the compressor 21 isdecreased (for example, the cooling power is 55), the currenttemperature is sensed after the sampling time, and, when the differencebetween the previous temperature and the current temperature is greaterthan 0 and the absolute value of the difference between the previoustemperature and the current temperature is equal to or greater than thefirst reference value, the cooling power of the compressor 21 may bedecreased again (for example, the cooling power is 50).

In addition, in a state in which the cooling power of the compressor 21is increased (for example, the cooling power is 65), the currenttemperature is sensed after the sampling time, and, when the differencebetween the previous temperature and the current temperature is lessthan 0 and the absolute value of the difference between the previoustemperature and the current temperature is equal to or greater than thefirst reference value, the cooling power of the compressor 21 may beincreased again (for example, the cooling power is 70).

As the temperature of the storage compartment is sensed at the samplingtime interval and the cooling power of the cool air supply means iscontrolled, the temperature of the storage compartment converges to theset temperature as long as there are no external influences.

FIG. 6 is a flowchart illustrating a method of controlling arefrigerator according to a second embodiment of the present invention.

The present embodiment is equal to the previous embodiment except thatthe kinds of factors for controlling the refrigerator are different.Accordingly, hereinafter, the characteristic portions of the presentembodiment will be described.

Referring to FIG. 6, steps S1 to S4 of the first embodiment are equallyapplicable to the control method of the present embodiment.

That is, when the refrigerator is turned on, the compressor is stoppedafter performing preliminary operation and, upon determining that theconstant temperature control start condition is satisfied, constanttemperature control of the storage compartment is performed.

At this time, when the constant temperature control start condition issatisfied, the temperature of the storage compartment may reach aspecific temperature within the temperature satisfaction range. Forexample, when the temperature of the storage compartment reaches the settemperature of the storage compartment, the compressor may operate.

In the present embodiment, the constant temperature control step mayinclude step S5 of sensing the temperature of the storage compartment ata predetermined time interval and step S15 of controlling the output ofthe cool air supply means.

For example, the controller 50 controls the output of the cool airsupply means using the difference between the set temperature and thecurrent temperature of the storage compartment (S15).

At this time, the controller 50 may sense the current temperature of thestorage compartment at the predetermined time interval and control theoutput of the cool air supply means based on whether the absolute valueof the difference between the set temperature and the currenttemperature is less than a first upper limit reference value or a firstlower limit reference value.

For example, a temperature higher than the set temperature by the firstupper limit reference value may be referred to as a temperature upperlimit (reference temperature C1) and a temperature lower than the settemperature by the first lower limit reference value may be referred toas a temperature lower limit (reference temperature C2).

The first upper limit reference value and the first lower limitreference value may be equal or different.

The first upper limit reference value and the first lower limitreference value may be set to 0.5 or the first upper limit referencevalue may be greater or less than the first lower limit reference value.

When the absolute value of the difference between the set temperatureand the current temperature is less than the first lower limit referencevalue or the first upper limit reference value, the current temperaturemay be lower than the temperature upper limit and higher than thetemperature lower limit.

Accordingly, when the current temperature is lower than the temperatureupper limit and higher than the temperature lower limit, the currenttemperature will be described as being located in the temperaturesatisfaction range.

In addition, when the current temperature is higher than the temperatureupper limit, the current temperature will be described as being locatedin the temperature upper limit excess range and, when the currenttemperature is lower than the temperature lower limit, the currenttemperature will be described as being located in the temperature lowerlimit excess range.

At this time, the temperature upper limit is a temperature value lowerthan the ON reference temperature A1 and higher than the set temperatureand the temperature lower limit is a temperature value higher than theOFF reference temperature A2 and lower than the set temperature.

The controller 50 senses the current temperature at the predeterminedtime interval. Accordingly, the predetermined time is a sampling timefor determining change in temperature.

At this time, the sampling time may be constant or changed according tothe current temperature. For example, if the current temperature islocated in the temperature satisfaction range, a first sampling time isapplicable as a sampling time for sensing a current temperature of anext time.

In contrast, if the current temperature is located outside thetemperature satisfaction range, a second sampling time greater or lessthan the first sampling time is applicable as a sampling time forsensing a current temperature of a next time.

The controller 50 continuously performs constant temperature controlunless the refrigerator 1 is turned off (S7).

FIG. 7 is a graph illustrating change in temperature of a storagecompartment and output control of a cool air supply means according tothe second embodiment.

FIG. 7 shows change in cooling power of the compressor for maintainingthe freezing compartment at a constant temperature and change intemperature of the freezing compartment. Numbers on the graph areexamples of the cooling power of the compressor.

Hereinafter, control of the cooling power of the compressor as anexample of the cool air supply means will be described.

Referring to FIG. 7, after the refrigerator is turned on or defrostingoperation is finished, the compressor 21 may operate with the maximumcooling power in order to rapidly decrease the temperature of thefreezing compartment. When the temperature of the freezing compartmentreaches the OFF reference temperature A2, the compressor 21 is stopped.

When the compressor 21 is stopped, the temperature of the freezingcompartment is increased and, when the temperature of the freezingcompartment reaches the set temperature Notch, constant temperaturecontrol of the freezing compartment may start.

When constant temperature control of the freezing compartment starts,the compressor 21 operates with predetermined cooling power betweenminimum cooling power and maximum cooling power.

As described above, the temperature of the freezing compartment issensed at a sampling time interval, and the controller 50 controls thecooling power of the compressor 21 based on a difference between the settemperature and a current temperature.

For example, while the compressor 21 operates with cooling power of 60,the cooling power may be maintained (cooling power: 60), decreased(cooling power: 55 or 50) or increased (cooling power: 65) according tothe temperature of the freezing compartment.

For example, when an absolute value of the difference between the settemperature and the current temperature is less than a first upper limitreference value or a first lower limit reference value, the controller50 may maintain the cooling power of the compressor 21.

For example, when the current temperature is located in the temperaturesatisfaction range, the cooling power of the compressor 21 may bemaintained.

In contrast, when the current temperature is located in the temperatureupper limit excess range, the cooling power of the compressor 21 may beincreased. In addition, when the current temperature is located in thetemperature lower limit excess range, the cooling power of thecompressor 21 may be decreased.

For example, when the current temperature is located in the temperaturelower limit excess range and the absolute value of the differencebetween the set temperature and the current temperature is greater thanthe first lower limit reference value and is less than the second lowerlimit reference value, the cooling power of the compressor 21 may bedecreased by a first level.

Alternatively, when the current temperature is located in thetemperature lower limit excess range and the absolute value of thedifference between the set temperature and the current temperature isgreater than the second lower limit reference value and is less than thethird lower limit reference value, the cooling power of the compressor21 may be decreased by a second level.

Alternatively, when the current temperature is located in thetemperature lower limit excess range and the absolute value of thedifference between the set temperature and the current temperature isequal to and greater than the third lower limit reference value, thecooling power of the compressor 21 may be decreased by a third level.

At this time, the second lower limit reference value is greater than thefirst lower limit reference value and the third lower limit referencevalue is greater than the second lower limit reference value.

For example, when the current temperature is located in the temperatureupper limit excess range and the absolute value of the differencebetween the set temperature and the current temperature is greater thanthe first upper limit reference value and is less than the second upperlimit reference value, the cooling power of the compressor 21 may beincreased by a first level.

Alternatively, when the current temperature is located in thetemperature upper limit excess range and the absolute value of thedifference between the set temperature and the current temperature isgreater than the second upper limit reference value and is less than thethird upper limit reference value, the cooling power of the compressor21 may be increased by a second level.

Alternatively, when the current temperature is located in thetemperature upper limit excess range and the absolute value of thedifference between the set temperature and the current temperature isequal to and greater than the third upper limit reference value, thecooling power of the compressor 21 may be increased by a third level.

In the present embodiment, the differences between the plurality oflevels may be equal or different.

For example, the first level may be set to A as a cooling power changevalue, the second level may be set to 2*A as a cooling power changevalue, and the third level may be set to 3*A as a cooling power changevalue. Alternatively, the first level may be set to A as a cooling powerchange value, the second level may be set to B (greater than A) which isnot 2*A as a cooling power change value, and the third level may be setto C (greater than B) which is not 3*A as a cooling power change value.

In addition, in the present embodiment, the differences between theplurality of upper limit reference values or the plurality of lowerlimit reference values may be equal or different.

For example, the first upper limit reference value may be set to 0.5,the second upper limit reference value may be set to 1, and the thirdupper limit reference value may be set to 1.5. Alternatively, the firstupper limit reference value may be set to 0.5, the second upper limitreference value may be set to 0.9, and the third upper limit referencevalue may be set to 1.3.

Meanwhile, in a state in which the cooling power of the compressor 21 isdecreased (for example, the cooling power is decreased from 60 to 55),the current temperature is sensed after the sampling time, and when thecurrent temperature is located in the temperature lower limit excessrange (for example, when the absolute value of the difference betweenthe set temperature and the current temperature is greater than thefirst lower limit reference value and is less than the second lowerlimit reference value), the cooling power of the compressor 21 may bedecreased again (for example, the cooling power is decreased from 55 to50).

In addition, in a state in which the cooling power of the compressor 21is increased (for example, the cooling power is decreased from 45 to50), the current temperature is sensed after the sampling time, and whenthe current temperature is located in the temperature upper limit excessrange (for example, when the absolute value of the difference betweenthe set temperature and the current temperature is greater than thesecond upper limit reference value and is less than the third upperlimit reference value), the cooling power of the compressor 21 may beincreased again (for example, the cooling power is increased from 50 to60).

As the temperature of the storage compartment is sensed at the samplingtime interval and the cooling power of the cool air supply means iscontrolled, the temperature of the storage compartment converges to theset temperature as long as there are no external influences.

FIG. 8 is a flowchart illustrating a method of controlling arefrigerator according to a third embodiment of the present invention.

The present embodiment is equal to the previous embodiments except thatthe kinds of factors for controlling the refrigerator are different.Accordingly, hereinafter, the characteristic portions of the presentembodiment will be described.

Referring to FIG. 8, steps S1 to S4 of the first embodiment are equallyapplicable to the control method of the present embodiment.

That is, when the refrigerator is turned on, the cool air supply meansis stopped after performing preliminary operation and, upon determiningthat the constant temperature control start condition is satisfied,constant temperature control of the storage compartment is performed.

At this time, when the constant temperature control start condition issatisfied, the temperature of the storage compartment may reach aspecific temperature within the temperature satisfaction range. Forexample, when the temperature of the storage compartment reaches the settemperature of the storage compartment, the cool air supply means mayoperate.

In the present embodiment, the constant temperature control step mayinclude step S5 of sensing the temperature of the storage compartment ata predetermined time interval and step S16 of controlling the output ofthe cool air supply means.

In the present embodiment, the controller 50 controls the output of thecool air supply means in order to perform constant temperature controlof the storage compartment. The controller 50 controls the output of thecool air supply means based on the temperature of the storagecompartment. For example, the controller 50 may control the output ofthe cool air supply means such that the temperature of the storagecompartment is maintained within the temperature satisfaction range.

Specifically, the controller 50 controls the output of the cool airsupply means using the change in temperature of the storage compartmentdescribed in the first embodiment and the difference between the settemperature and the current temperature of the storage compartmentdescribed in the second embodiment (S16).

Accordingly, hereinafter, the terms used in the first embodiment and theterms used in the second embodiment are equally used.

In the present embodiment, as change in temperature of the storagecompartment, the difference between the previous temperature and thecurrent temperature is used. Change in temperature of the storagecompartment is based on the temperature value of the storage compartmentsensed at a predetermined time interval. Accordingly, the predeterminedtime is a sampling time for determining change in temperature.

The output of the cool air supply means may be decreased, maintained orincreased according to a first factor (the difference between theprevious temperature and the current temperature) for controlling theoutput of the cool air supply means and a second factor (the differencebetween the set temperature and the current temperature).

For example, the controller 50 determines whether the output of the coolair supply means is increased, maintained or decreased based on thefirst factor, determines whether the output of the cool air supply meansis increased, maintained or decreased based on the second factor, andthen finally determines whether the output of the cool air supply meansis increased, maintained or decreased by combining the results.

For example, upon determining that the output of the cool air supplymeans is maintained based on the first factor and determining that theoutput of the cool air supply means is increased based on the secondfactor, the output of the cool air supply means is finally increased.

Upon determining that the output of the cool air supply means ismaintained based on the first factor and determining that the output ofthe cool air supply means is decreased based on the second factor, theoutput of the cool air supply means is finally decreased.

Upon determining that the output of the cool air supply means ismaintained based on the first factor and the second factor, the outputof the cool air supply means is finally maintained.

Upon determining that the output of the cool air supply means isincreased based on the first factor and determining that the output ofthe cool air supply means is maintained based on the second factor, theoutput of the cool air supply means is finally increased.

Upon determining that the output of the cool air supply means isdecreased based on the first factor and determining that the output ofthe cool air supply means is maintained based on the second factor, theoutput of the cool air supply means is finally decreased.

Upon determining that the output of the cool air supply means isincreased based on the first factor and the second factor, the output ofthe cool air supply means is finally increased.

Upon determining that the output of the cool air supply means isdecreased based on the first factor and the second factor, the output ofthe cool air supply means is finally decreased.

Upon determining that the output of the cool air supply means isdecreased based on the first factor and determining that the output ofthe cool air supply means is increased based on the second factor, theoutput of the cool air supply means may be finally maintained, increasedor decreased according to the level of the decreased output determinedbased on the first factor and the level of the increased outputdetermined based on the second factor.

Upon determining that the output of the cool air supply means isincreased based on the first factor and determining that the output ofthe cool air supply means is decreased based on the second factor, theoutput of the cool air supply means may be finally maintained, increasedor decreased according to the level of the increased output determinedbased on the first factor and the level of the decreased outputdetermined based on the second factor.

In addition, after the output of the cool air supply means isdetermined, the determined output is maintained during the sampling timeand, when the sampling time has elapsed, the output of the cool airsupply means is determined again. That is, the output of the cool airsupply means may be controlled at the sampling time interval. Inaddition, the controller controls the cool air supply means such thatthe cool air supply means operates with the determined output during thesampling time.

The controller 50 continuously performs constant temperature controlunless the refrigerator 1 is turned off (S7).

Hereinafter, for example, a detailed method of controlling the output ofthe cool air supply means for constant temperature control will bedescribed.

FIGS. 9 to 12 are flowcharts illustrating the method of controlling theoutput of the cool air supply means according to the third embodiment.

At a constant temperature control start time, the output of the cool airsupply means may be set to a predetermined output between a minimumoutput and a maximum output (hereinafter, referred to as an initialoutput).

Referring to FIGS. 9 to 12, the controller 50 performs control such thatthe cool air supply means operate with the initial output in order toperform constant temperature control in a state in which the currenttemperature of the storage compartment reaches the set temperature. Forexample, the compressor and the fan driver may operate with initialoutput and the damper 12 may be opened at an initial angle greater than0.

When the sample time has elapsed while the cool air supply meansoperates with the initial output, the temperature of the storagecompartment is sensed by the temperature sensors 41 and 42.

Next, the controller 50 determines whether a difference between theprevious temperature and the current temperature of the storagecompartment sensed by the temperature sensors 41 and 42 is greater than0 (S51). Here, the previous temperature upon initial constanttemperature control may be a set temperature.

If the difference between the previous temperature and the currenttemperature is greater than 0, the temperature of the storagecompartment is decreased.

Upon determining that the difference between the previous temperatureand the current temperature is greater than 0 in step S51, thecontroller 50 determines whether the difference between the previoustemperature and the current temperature is less than a first referencevalue (S52).

Upon determining that the difference between the previous temperatureand the current temperature is less than the first reference value instep S52, the controller 50 determines that the output of the cool airsupply means is maintained as a result of determination based on thefirst factor.

Next, the controller 50 determines whether the difference between theset temperature and the current temperature is less than 0 (S53).

When the difference between the set temperature and the currenttemperature is less than 0, the current temperature is greater than theset temperature and, the difference between the set temperature and thecurrent temperature is equal to or greater than 0, the currenttemperature is equal to or less than the set temperature.

Upon determining that the difference between the set temperature and thecurrent temperature is less than 0 in step S53, the controller 50 maydetermine whether the current temperature is in a temperaturesatisfaction range (S54).

When the difference between the set temperature and the currenttemperature is less than a unit temperature, the current temperature isclose to the set temperature.

Upon determining that the current temperature is in the temperaturesatisfaction range in step S54, the controller 50 determines that theoutput of the cool air supply means is maintained as the result ofdetermination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is maintained according to theresult (S51 and S52) of determination based on the first factor and theresult (S53 and S54) of determination based on the second factor (S55).

In contrast, upon determining that the current temperature is out of thetemperature satisfaction range in step S54 (when the current temperatureis in the temperature upper limit excess range), the controller 50determines that the output of the cool air supply means is increased asthe result of determination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is increased according to the result(S51 and S52) of determination based on the first factor and the result(S53 and S54) of determination based on the second factor (S56).

At this time, when the current temperature is in the temperature upperlimit excess range, the absolute value of the difference between the settemperature and the current temperature is compared with the pluralityof upper limit reference values to make increase in output of the coolair supply means different.

For example, as described in the second embodiment, when the absolutevalue of the difference between the set temperature and the currenttemperature is greater than a first upper limit reference value and isless than a second upper limit reference value while the currenttemperature is in the temperature upper limit excess range, the outputof the cool air supply means may be increased by the first level.

When the absolute value of the difference between the set temperatureand the current temperature is greater than the second upper limitreference value and is less than a third upper limit reference valuewhile the current temperature is in the temperature upper limit excessrange, the output of the cool air supply means may be increased by thesecond level.

When the absolute value of the difference between the set temperatureand the current temperature is greater than the third upper limitreference value while the current temperature is in the temperatureupper limit excess range, the output of the cool air supply means may beincreased by the third level.

In contrast, upon determining that the difference between the settemperature and the current temperature is equal to or greater than 0 instep S53, the controller 50 may determine that the current temperatureis in the temperature satisfaction range (S61).

Upon determining that the current temperature is in the temperaturesatisfaction range in step S61, the controller 50 determines that theoutput of the cool air supply means is maintained as the result ofdetermination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is maintained according to theresult (S51 and S52) of determination based on the first factor and theresult (S53 and S61) of determination based on the second factor (S62).

In contrast, upon determining that the current temperature is out of thetemperature satisfaction range in step S61 (when the current temperatureis in the temperature lower limit excess range), the controller 50determines that the output of the cool air supply means is decreased asthe result of determination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is decreased according to the result(S51 and S52) of determination based on the first factor and the result(S53 and S61) of determination based on the second factor (S63).

At this time, when the current temperature is in the temperature lowerlimit excess range, the absolute value of the difference between the settemperature and the current temperature is compared with the pluralityof lower limit reference values to make decrease in output of the coolair supply means different.

For example, as described in the second embodiment, when the absolutevalue of the difference between the set temperature and the currenttemperature is greater than a first lower limit reference value and isless than a second lower limit reference value while the currenttemperature is in the temperature lower limit excess range, the outputof the cool air supply means may be decreased by the first level.

When the absolute value of the difference between the set temperatureand the current temperature is greater than the second lower limitreference value and is less than a third lower limit reference valuewhile the current temperature is in the temperature lower limit excessrange, the output of the cool air supply means may be decreased by thesecond level.

When the absolute value of the difference between the set temperatureand the current temperature is greater than the third lower limitreference value while the current temperature is in the temperaturelower limit excess range, the output of the cool air supply means may bedecreased by the third level.

In contrast, upon determining that the difference between the previoustemperature and the current temperature is equal to or greater than afirst reference value in step S52, the controller 50 may determine thatthe output of the cool air supply means is decreased as the result ofdetermination based on the first factor.

Next, the controller 50 may determine whether the difference between theset temperature and the current temperature is greater than 0 (S71).

Upon determining that the difference between the set temperature and thecurrent temperature is greater than 0 in step S71, the controller 50 maydetermine that the output of the cool air supply means is maintained ordecreased according to the difference between the set temperature andthe current temperature (depending on whether the current temperature isin the temperature satisfaction range).

At this time, when the current temperature is in the temperaturesatisfaction range, it may be determined that the output of the cool airsupply means is maintained and, when the current temperature is out ofthe temperature satisfaction range (when the current temperature is inthe temperature lower limit excess range), the decrease level of theoutput of the cool air supply means may be determined according to theabsolute value of the difference between the set temperature and thecurrent temperature.

In either case, the controller 50 finally determines that the currentoutput of the cool air supply means is decreased according to the result(S51 and S52) of determination based on the first factor and the result(S71) of based on the second factor (S72).

In contrast, upon determining that the difference between the settemperature and the current temperature is equal to or less than 0 instep S71, the controller 50 may determine whether the currenttemperature is in the temperature satisfaction range (S73).

Upon determining that the current temperature is in the temperaturesatisfaction range in step S73, the controller 50 determines that theoutput of the cool air supply means is maintained as the result ofdetermination based on the second factor.

Accordingly, the controller 50 determines that the current out of thecool air supply means is decreased according to the result (S51 and S52)of determination based on the first factor and the result (S71 and S73)of determination based on the second factor (S74).

Upon determining that the current temperature is out of the temperaturesatisfaction range (when the current temperature is in the temperatureupper limit excess range, the controller 50 determines that the outputof the cool air supply means is increased as the result of determinationbased on the second factor.

In this case, the controller 50 may maintain, increase or decrease theoutput of the cool air supply means according to the result (S51 andS52) of determination based on the first factor and the result (S71 andS73) of determination based on the second factor.

For example, the output of the cool air supply means may be maintained,increased or decreased according to the level of the output of the coolair supply means decreased as the result of determination based on thefirst factor and the level of the output of the cool air supply meansincreased as the result of determination based on the second factor.

That is, when the output of the cool air supply means decreased as theresult of determination based on the first factor and the output of thecool air supply means increased based on the second factor are equal,the controller 50 may determine that the output of the cool air supplymeans is maintained.

When the output of the cool air supply means decreased as the result ofdetermination based on the first factor is greater than the output ofthe cool air supply means increased as the result of determination basedon the second factor, the controller 50 may determine that the output ofthe cool air supply means is decreased.

When the output of the cool air supply means decreased as the result ofdetermination based on the first factor is less than the output of thecool air supply means increased as the result of determination based onthe second factor, the controller 50 may determine that the output ofthe cool air supply means is increased.

Meanwhile, upon determining that the difference between the previoustemperature and the current temperature is equal to or less than 0 instep S51, the controller 50 may determine whether the difference betweenthe previous temperature and the current temperature is less than afirst reference value (S81).

Here, when the difference between the previous temperature and thecurrent temperature is equal to or less than 0, the temperature of thestorage compartment is maintained or is increased during the samplingtime.

Upon determining that the difference between the previous temperatureand the current temperature is less than the first reference value instep S81, the controller 50 determines that the output of the cool airsupply means is maintained as the result of determination based on thefirst factor.

The controller 50 determines whether the difference between the settemperature and the current temperature is greater than 0 (S82).

Upon determining that the difference between the set temperature and thecurrent temperature is greater than 0 in step S82, whether the currenttemperature is in the temperature satisfaction range is determined(S83).

Upon determining that the current temperature is in the temperaturesatisfaction range in step S83, the controller 50 determines that theoutput of the cool air supply means is maintained as the result ofdetermination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is maintained according to theresult (S51 and S81) based on the first factor and the result (S82 andS83) based on the second factor (S84).

In contrast, upon determining that the current temperature is out of thetemperature satisfaction range in step S83 (when the current temperatureis in the temperature lower limit excess range), the controller 50determines that the output of the cool air supply means is decreased asthe result of determination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is decreased according to the result(S51 and S81) based on the first factor and the result (S82 and S83)based on the second factor (S85).

Meanwhile, upon determining that the difference between the settemperature and the current temperature is equal to or less than 0 instep S82, the controller 50 determines whether the current temperatureis in the temperature satisfaction range (S86).

Upon determining that the current temperature is in the temperaturesatisfaction range in step S86, the controller 50 determines that theoutput of the cool air supply means is maintained as the result ofdetermination based on the second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is maintained according to theresult (S51 and S81) based on the first factor and the result (S82 andS83) based on the second factor (S85).

In contrast, upon determining that the current temperature is out of thetemperature satisfaction range (when the current temperature is in thetemperature upper limit excess range), the controller 50 may determinethe increase level of the output of the cool air supply means accordingto the comparison between the absolute value of the difference betweenthe set temperature and the current temperature as the result ofdetermination based on the second factor and the plurality of referencevalues.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is increased according to the result(S51 and S81) based on the first factor and the result (S82 and S83)based on the second factor (S88).

Meanwhile, upon determining that the difference between the previoustemperature and the current temperature is equal to or greater than thefirst reference value in step S81, the controller 50 determines that theoutput of the cool air supply means is increased as the result ofdetermination based on the first factor.

The controller 50 may determine that the difference between the settemperature and the current temperature is greater than 0 (S91).

Upon determining that the difference between the set temperature and thecurrent temperature is greater than 0 in step S91, the controller 50 maydetermine that the current temperature is in the temperaturesatisfaction range (S92).

Upon determining that the current temperature is in the temperaturesatisfaction range in step S92, the controller 50 determines that theoutput of the cool air supply means is maintained as the result based onthe second factor.

Accordingly, the controller 50 finally determines that the currentoutput of the cool air supply means is increased according to the result(S51 and S81) based on the first factor and the result (S91 and S92)based on the second factor (S93).

In contrast, when the current temperature is out of the temperaturesatisfaction range (when the current temperature is in the temperaturelower limit excess range), the controller 50 determines that the outputof the cool air supply means is decreased as the result of determinationbased on the second factor.

In this case, the controller 50 may maintain, increase or decrease theoutput of the cool air supply means based on the result (S51 and S81)based on the first factor and the result (S91 and S92) based on thesecond factor (S94).

For example, whether the output of the cool air supply means ismaintained, increased or decreased may be determined according to theoutput level of the cool air supply means increased based on the resultbased on the first factor and the output level of the cool air supplymeans decreased based on the result based on the second factor.

That is, when the output of the cool air supply means increased as theresult based on the first factor and the output of the cool air supplymeans decreased based on the result based on the second factor areequal, the controller 50 may determine that the output of the cool airsupply means is maintained.

When the output of the cool air supply means increased as the resultbased on the first factor is greater than the output of the cool airsupply means decreased based on the result based on the second factor,the controller 50 may determine that the output of the cool air supplymeans is increased.

When the output of the cool air supply means increased as the resultbased on the first factor is less than the output of the cool air supplymeans decreased based on the result based on the second factor, thecontroller 50 may determine that the output of the cool air supply meansis decreased.

Meanwhile, upon determining that the difference between the settemperature and the current temperature is equal to or less than 0 instep S91, the controller 50 may determine that the output of the coolair supply means is maintained or increased as the result based on thesecond factor according to the level of the absolute value of thedifference between the set temperature and the current temperature.

At this time, when the absolute value of the difference between the settemperature and the current temperature is less than a first referencevalue, it may be determined that the output of the cool air supply meansis maintained.

When the absolute value of the difference between the set temperatureand the current temperature is equal to or greater than the firstreference value, the increase level of the output of the cool air supplymeans may be determined according to the comparison between the absolutevalue of the difference between the set temperature and the currenttemperature and the plurality of reference values.

In either case, the controller 50 determines that the current output ofthe cool air supply means is increased according to the result (S51 andS52) of determination based on the first factor and the result (S71) ofbased on the second factor (S95).

FIG. 13 is a graph illustrating change in temperature of a storagecompartment and output control of a cool air supply means according tothe third embodiment.

FIG. 13 shows change in cooling power of the compressor for maintainingthe freezing compartment at a constant temperature and change intemperature of the freezing compartment. Numbers on the graph areexamples of the cooling power of the compressor.

Referring to FIG. 13, after the refrigerator is turned on or defrostingoperation is finished, the compressor 21 may operate with the maximumcooling power in order to rapidly decrease the temperature of thefreezing compartment. When the temperature of the freezing compartmentreaches the lower limit temperature, the compressor 21 is stopped.

When the compressor 21 is stopped, the temperature of the freezingcompartment is increased and, when the temperature of the freezingcompartment reaches the set temperature Notch, constant temperaturecontrol of the freezing compartment may start.

As described above, the temperature of the freezing compartment issensed at a sampling time interval, and the controller 50 controls thecooling power of the compressor 21 based on the first factor and thesecond factor.

For example, while the compressor 21 operates with cooling power of 60,the cooling power may be maintained (cooling power: 60), decreased(cooling power: 55, 45, 40 or 35) or increased (cooling power: 70 or 65)according to the temperature of the freezing compartment.

At this time, when the door of the refrigerator is opened to increasethe temperature of the storage compartment or when food is furtherintroduced into the storage compartment, the storage compartment isoverheated and, when the temperature of the storage compartment is equalto or greater than the reference temperature A1, the controller 50 mayperform control such that the cool air supply means operates with thepredetermined first output value, for example, the maximum output value,in order to rapidly decrease the temperature of the storage compartment.

For example, the controller 50 performs control such that the cool airsupply means operates with the predetermined first output value, forexample, the maximum output value, during the sampling time or until thetemperature of the storage compartment reaches a specific temperature inthe temperature satisfaction range.

As the temperature of the storage compartment is sensed at the samplingtime interval and the cooling power of the cool air supply means iscontrolled, the temperature of the storage compartment converges to theset temperature as long as there are no external influences.

In order to maintain the temperature of the storage compartment close tothe set temperature, the output of the cool air supply means may bemaintained at a specific output through the output control process.

According to the proposed embodiment, since the temperature of thestorage compartment can be constantly maintained, the storage period offood can be increased. That is, the food stored in the storagecompartment can be prevented from being overcooled or wilted.

In addition, in order to constantly maintain the temperature of thestorage compartment, since a cool air supply means is not stopped and ismaintained in a driving state (continuous operation), power consumed forinitial startup of the cool air supply means can be reduced.

In addition, since the output of the cool air supply means is controlledbased on a difference between a previous temperature and a currenttemperature and/or a difference between a set temperature and a currenttemperature, it is possible to rapidly return to a constant temperaturewhen the temperature of the storage compartment deviates from theconstant temperature.

1. A method of controlling a refrigerator, the method comprising:operating a cool air supply means with a predetermined output; acontroller determining the output of the cool air supply means based ona current temperature of a storage compartment sensed by a temperaturesensor while the cool air supply means operates with the predeterminedoutput; and the controller operating the cool air supply means with thedetermined output, wherein the controller determines that the output ofthe cool air supply means is decreased or increased when an absolutevalue of a difference between a previous temperature and a currenttemperature of the storage compartment is equal to or greater than afirst reference value, and wherein the output of the cool air supplymeans is decreased or increased again when the absolute value of thedifference between a current temperature of the storage compartmentsensed again after a predetermined time has elapses and the previoustemperature of the storage compartment is equal to or greater than thefirst reference value.
 2. The method of claim 1, wherein the controllerdetermines that the output of the cool air supply means is decreasedwhen the difference between the previous temperature and the currenttemperature of the storage compartment is greater than 0 and theabsolute value of the difference between the previous temperature andthe current temperature of the storage compartment is equal to orgreater than the first reference value.
 3. The method of claim 1,wherein the controller determines that the output of the cool air supplymeans is increased when the difference between the previous temperatureand the current temperature of the storage compartment is less than 0and the absolute value of the difference between the previoustemperature and the current temperature of the storage compartment isequal to or greater than the first reference value.
 4. The method ofclaim 1, wherein the controller determines that the output of the coolair supply means is decreased or increased by a first level when theabsolute value of the difference between the previous temperature andthe current temperature of the storage compartment is equal to orgreater than the first reference value and is less than a secondreference value greater than the first reference value, and determinesthat the output of the cool air supply means is decreased or increasedby a second level greater than the first level when the absolute valueof the difference between the previous temperature and the currenttemperature of the storage compartment is equal to or greater than thesecond reference value.
 5. The method of claim 4, wherein a differencebetween the second reference value and the first reference value, andthe first reference value are equal or different.
 6. The method of claim4, wherein, when change in the output of the cool air supply meanscorresponding to the first level is referred to as a first output changevalue and change in the output of the cool air supply meanscorresponding to the second level is referred to as a second outputchange value, a difference between the second output change value andthe first output change value is equal to or different from the firstoutput change value.
 7. The method of claim 1, wherein the controllerdetermines that the output of the cool air supply means is maintainedwhen the absolute value of the difference between the previoustemperature and the current temperature of the storage compartment isless than the first reference value.
 8. The method of claim 1, whereinthe cool air supply means includes one or more of a compressorconfigured to compress refrigerant and a fan driver configured to drivea fan for blowing air heat-exchanged with an evaporator to the storagecompartment.
 9. The method of claim 1, wherein the storage compartmentis a refrigerating compartment, and wherein the cool air supply meansincludes a damper driver configured to drive a damper provided in a ductfor guiding cool air of a freezing compartment to the refrigeratingcompartment.
 10. A method of controlling a refrigerator, the methodcomprising: operating a cool air supply means with a predeterminedoutput; a controller determining the output of the cool air supply meansbased on a current temperature of a storage compartment sensed by atemperature sensor while the cool air supply means operates with thepredetermined output; and the controller operating the cool air supplymeans with the determined output, wherein the controller determines thatthe output of the cool air supply means is decreased or increased whenan absolute value of a difference between a set temperature and acurrent temperature of the storage compartment is equal to or greaterthan a first reference value, and wherein the output of the cool airsupply means is decreased or increased again when the absolute value ofthe difference between the set temperature and a current temperature ofthe storage compartment sensed again after a predetermined time haselapses is equal to or greater than the first reference value.
 11. Themethod of claim 10, wherein the first reference value includes a firstupper limit reference value higher than the set temperature, andwherein, when the current temperature is higher than the set temperatureand the absolute value of the difference between the set temperature andthe current temperature exceeds the first upper limit reference value,the controller determines that the output of the cool air supply meansis increased.
 12. The method of claim 10, wherein the first referencevalue includes a first lower limit reference value lower than the settemperature, and wherein, when the current temperature is lower than theset temperature and the absolute value of the difference between the settemperature and the current temperature exceeds the first lower limitreference value, the controller determines that the output of the coolair supply means is decreased.
 13. The method of claim 10, wherein thecontroller determines that the output of the cool air supply means isdecreased or increased by a first level when the absolute value of thedifference between the set temperature and the current temperature ofthe storage compartment is equal to or greater than the first referencevalue and is less than a second reference value greater than the firstreference value, and determines that the output of the cool air supplymeans is decreased or increased by a second level greater than the firstlevel when the absolute value of the difference between the settemperature and the current temperature of the storage compartment isequal to or greater than the second reference value.
 14. The method ofclaim 13, wherein a difference between the second reference value andthe first reference value, and the first reference value are equal ordifferent.
 15. The method of claim 13, wherein, when change in theoutput of the cool air supply means corresponding to the first level isreferred to as a first output change value and change in the output ofthe cool air supply means corresponding to the second level is referredto as a second output change value, a difference between the secondoutput change value and the first output change value is equal to ordifferent from the first output change value.
 16. The method of claim10, wherein the controller determines that the output of the cool airsupply means is maintained when the absolute value of the differencebetween the set temperature and the current temperature of the storagecompartment is less than the first reference value.
 17. The method ofclaim 10, wherein the cool air supply means includes one or more of acompressor configured to compress refrigerant and a fan driverconfigured to drive a fan for blowing air heat-exchanged with anevaporator to the storage compartment.
 18. The method of claim 10,wherein the storage compartment is a refrigerating compartment, andwherein the cool air supply means includes a damper driver configured todrive a damper provided in a duct for guiding cool air of a freezingcompartment to the refrigerating compartment.
 19. A method ofcontrolling a refrigerator, the method comprising: sensing whether therefrigerator is turned on; changing an output of a cool air supply meansto a predetermined first output value after the refrigerator is turnedon; stopping the cool air supply means when a temperature of a storagecompartment reaches an OFF reference temperature A2 lower than a settemperature of the storage compartment; a controller determining theoutput of the cool air supply means to a second output value lower thanthe predetermined first output value based on a current temperature of astorage compartment sensed by a temperature sensor when the temperatureof the storage compartment reaches a predetermined temperature; and thecontroller operating the cool air supply means with the determinedoutput, wherein the operating the cool air supply means with determinedsecond output includes: when a range between a temperature upper limitgreater than a set temperature of the storage compartment and atemperature lower limit less than the set temperature of the storagecompartment is a temperature satisfaction range, the controllerdetermining that the output of the cool air supply means is maintainedwhen the sensed current temperature is in the temperature satisfactionrange and an absolute value of a difference between a previoustemperature and the current temperature of the storage compartment isless than a first reference value, and the controller changing theoutput of the cool air supply means when the sensed current temperatureis out of the temperature satisfaction range or the absolute value ofthe difference between the previous temperature and the currenttemperature of the storage compartment is equal to or more than thefirst reference value, when it is determined that a refrigerator door isopened or the cool air supply means is stopped for defrosting, thecontroller determines the output of the cool air supply means to a thirdoutput value different from the second output value.